From e533825447dcb60a82b7cc9d73d06423c849b9a2 Mon Sep 17 00:00:00 2001 From: Jeff Garzik Date: Sun, 30 Oct 2005 21:37:17 -0500 Subject: [PATCH 1/2] [libata] ata_tf_to_host cleanups Integrate ata_exec() and ata_tf_to_host() into their only caller, ata_bus_edd(). Rename ata_tf_to_host_nolock() to ata_tf_to_host(). This makes locking a bit easier to review, and may help pave the way for future changes. --- drivers/scsi/libata-core.c | 57 +++++++------------------------------- drivers/scsi/libata.h | 1 - 2 files changed, 10 insertions(+), 48 deletions(-) diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c index 8be7dc0b47b8..a17e12032f65 100644 --- a/drivers/scsi/libata-core.c +++ b/drivers/scsi/libata-core.c @@ -294,28 +294,6 @@ void ata_exec_command(struct ata_port *ap, const struct ata_taskfile *tf) ata_exec_command_pio(ap, tf); } -/** - * ata_exec - issue ATA command to host controller - * @ap: port to which command is being issued - * @tf: ATA taskfile register set - * - * Issues PIO/MMIO write to ATA command register, with proper - * synchronization with interrupt handler / other threads. - * - * LOCKING: - * Obtains host_set lock. - */ - -static inline void ata_exec(struct ata_port *ap, const struct ata_taskfile *tf) -{ - unsigned long flags; - - DPRINTK("ata%u: cmd 0x%X\n", ap->id, tf->command); - spin_lock_irqsave(&ap->host_set->lock, flags); - ap->ops->exec_command(ap, tf); - spin_unlock_irqrestore(&ap->host_set->lock, flags); -} - /** * ata_tf_to_host - issue ATA taskfile to host controller * @ap: port to which command is being issued @@ -326,30 +304,11 @@ static inline void ata_exec(struct ata_port *ap, const struct ata_taskfile *tf) * other threads. * * LOCKING: - * Obtains host_set lock. - */ - -static void ata_tf_to_host(struct ata_port *ap, const struct ata_taskfile *tf) -{ - ap->ops->tf_load(ap, tf); - - ata_exec(ap, tf); -} - -/** - * ata_tf_to_host_nolock - issue ATA taskfile to host controller - * @ap: port to which command is being issued - * @tf: ATA taskfile register set - * - * Issues ATA taskfile register set to ATA host controller, - * with proper synchronization with interrupt handler and - * other threads. - * - * LOCKING: * spin_lock_irqsave(host_set lock) */ -void ata_tf_to_host_nolock(struct ata_port *ap, const struct ata_taskfile *tf) +static inline void ata_tf_to_host(struct ata_port *ap, + const struct ata_taskfile *tf) { ap->ops->tf_load(ap, tf); ap->ops->exec_command(ap, tf); @@ -1912,12 +1871,14 @@ static void ata_bus_post_reset(struct ata_port *ap, unsigned int devmask) * * LOCKING: * PCI/etc. bus probe sem. + * Obtains host_set lock. * */ static unsigned int ata_bus_edd(struct ata_port *ap) { struct ata_taskfile tf; + unsigned long flags; /* set up execute-device-diag (bus reset) taskfile */ /* also, take interrupts to a known state (disabled) */ @@ -1928,7 +1889,9 @@ static unsigned int ata_bus_edd(struct ata_port *ap) tf.protocol = ATA_PROT_NODATA; /* do bus reset */ + spin_lock_irqsave(&ap->host_set->lock, flags); ata_tf_to_host(ap, &tf); + spin_unlock_irqrestore(&ap->host_set->lock, flags); /* spec says at least 2ms. but who knows with those * crazy ATAPI devices... @@ -3555,7 +3518,7 @@ int ata_qc_issue_prot(struct ata_queued_cmd *qc) switch (qc->tf.protocol) { case ATA_PROT_NODATA: - ata_tf_to_host_nolock(ap, &qc->tf); + ata_tf_to_host(ap, &qc->tf); break; case ATA_PROT_DMA: @@ -3566,20 +3529,20 @@ int ata_qc_issue_prot(struct ata_queued_cmd *qc) case ATA_PROT_PIO: /* load tf registers, initiate polling pio */ ata_qc_set_polling(qc); - ata_tf_to_host_nolock(ap, &qc->tf); + ata_tf_to_host(ap, &qc->tf); ap->hsm_task_state = HSM_ST; queue_work(ata_wq, &ap->pio_task); break; case ATA_PROT_ATAPI: ata_qc_set_polling(qc); - ata_tf_to_host_nolock(ap, &qc->tf); + ata_tf_to_host(ap, &qc->tf); queue_work(ata_wq, &ap->packet_task); break; case ATA_PROT_ATAPI_NODATA: ap->flags |= ATA_FLAG_NOINTR; - ata_tf_to_host_nolock(ap, &qc->tf); + ata_tf_to_host(ap, &qc->tf); queue_work(ata_wq, &ap->packet_task); break; diff --git a/drivers/scsi/libata.h b/drivers/scsi/libata.h index 10ecd9e15e4f..fad051ca4672 100644 --- a/drivers/scsi/libata.h +++ b/drivers/scsi/libata.h @@ -48,7 +48,6 @@ extern int ata_qc_issue(struct ata_queued_cmd *qc); extern int ata_check_atapi_dma(struct ata_queued_cmd *qc); extern void ata_dev_select(struct ata_port *ap, unsigned int device, unsigned int wait, unsigned int can_sleep); -extern void ata_tf_to_host_nolock(struct ata_port *ap, const struct ata_taskfile *tf); extern void swap_buf_le16(u16 *buf, unsigned int buf_words); extern int ata_task_ioctl(struct scsi_device *scsidev, void __user *arg); extern int ata_cmd_ioctl(struct scsi_device *scsidev, void __user *arg); From 005a5a06a6dd13a0ca3f2c6a0218e8d94ed36d8a Mon Sep 17 00:00:00 2001 From: Jeff Garzik Date: Sun, 30 Oct 2005 23:31:48 -0500 Subject: [PATCH 2/2] [libata] locking rewrite (== fix) A lot of power packed into a little patch. This change eliminates the sharing between our controller-wide spinlock and the SCSI core's Scsi_Host lock. As the locking in libata was already highly compartmentalized, always referencing our own lock, and never scsi_host::host_lock. As a side effect, this change eliminates a deadlock from calling scsi_finish_command() while inside our spinlock. --- drivers/scsi/libata-core.c | 2 -- drivers/scsi/libata-scsi.c | 9 ++++++++- 2 files changed, 8 insertions(+), 3 deletions(-) diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c index a17e12032f65..ff18fa7044c5 100644 --- a/drivers/scsi/libata-core.c +++ b/drivers/scsi/libata-core.c @@ -4089,8 +4089,6 @@ static void ata_host_init(struct ata_port *ap, struct Scsi_Host *host, host->unique_id = ata_unique_id++; host->max_cmd_len = 12; - scsi_assign_lock(host, &host_set->lock); - ap->flags = ATA_FLAG_PORT_DISABLED; ap->id = host->unique_id; ap->host = host; diff --git a/drivers/scsi/libata-scsi.c b/drivers/scsi/libata-scsi.c index 1e3792f86fcf..248baae96486 100644 --- a/drivers/scsi/libata-scsi.c +++ b/drivers/scsi/libata-scsi.c @@ -39,6 +39,7 @@ #include #include "scsi.h" #include +#include #include #include #include @@ -2405,8 +2406,12 @@ int ata_scsi_queuecmd(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *)) struct ata_port *ap; struct ata_device *dev; struct scsi_device *scsidev = cmd->device; + struct Scsi_Host *shost = scsidev->host; - ap = (struct ata_port *) &scsidev->host->hostdata[0]; + ap = (struct ata_port *) &shost->hostdata[0]; + + spin_unlock(shost->host_lock); + spin_lock(&ap->host_set->lock); ata_scsi_dump_cdb(ap, cmd); @@ -2429,6 +2434,8 @@ int ata_scsi_queuecmd(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd *)) ata_scsi_translate(ap, dev, cmd, done, atapi_xlat); out_unlock: + spin_unlock(&ap->host_set->lock); + spin_lock(shost->host_lock); return 0; }